Load indicator for cranes



Jan. 6, 1948. c, 5; ADAMS LOAD INDICATOR FOR CRANES Filed March 11, 19464 Sheets-Sheet l Jan. 6, 1948. c, s, ADAMS 2,4

LOAD INDICATOR FOR CRANES Filed March 11, 1946 4 Sheets-Sheet 2 PPQQQJan. 6, 1948. 5 5, ADAMS 2,434,138

LOAD INDICATOR FOR CRANES Filed March 11, 1946 4 Sheets-Shee 4 Q9 30a 3k32 is operatively connected Patented Jan. e, 1948 UNITED STATES PATENTOFFICE 2,434,138 LOAD INDICATOR FOR CBANES Cyril S. Adams, Houston, Tex.I Application March 11, 1946, Serial No. 653,671 3 Claims. (CL 177-311)invention relates to a load indicator and to a load indicator for an ofelectrical signaling devices located at a convenient place in view ofthe operator with means for actuating the signals successively, as theload is increased, to warn the operator when the load limit has beenreached.

In the present illustration the signaling devices consist of electriclights although audible signals may be used.

The invention also comprehends means for electrically setting the brakeson the hoisting motor to prevent overloading of the crane.

Other objects and advantages will be apparent from the followingspecification which is illustrated in the accompanyingdrawings, wherein:

Figure 1 is a fragmentary, side view of an overhead crane, viewed asindicated by the line I--i of Figure 2 and showing the near bridgegirder partly broken away.

Figure 2 is an end elevation viewed as indicated by the line 2-2 ofFigure 1.

Figure 3 is an elevation, partly in section, of the tension springemployed and associated parts.

Figure 4 is a sectional .view thereof taken at right angles to the viewshown in Figure 4, and;

Figure 5 is a wiring diagram.

Referring now more particularly to the drawings wherein like numerals ofreference designate the same parts in each of the figures, the numeralsI and 2 designate similar spaced bridge girders which are supported attheir respective ends on similar carriages, as 3. Each carriage isprovided with the supporting wheels I, 4 which travel on suitablysupported rails 5.

Mounted on the bridge girders are the trolley rails 6, 6 provided tosupport the trolley I. This trolley is provided with the supportingwheels 8, 8 which travel along the rails 6. Mounted on the trolley Ithere is a cable winding drum 3 which with a hoisting motor (not shownin the present drawings).

There is a traveling block l containing the sheaves II, II over whichthe runs l2, l2 of the hoisting cable operate. The ends of this cableare wound about the drum 3 and the lifting and the operator. The blockIII is equipped with the usual depending hook I3 by means of which theload to be lifted may be attached to the block.

' Mounted on the trolley I are the spaced brackets ll, II which areprovided with suitable aligned bearings through which a supporting rod iextends. This rod also extends through, and supports, an upper connectorl8. Spaced beneath the connector I6 is a lower connector IT. Theadjacent'ends of these connectors are threaded into, or otherwisefastened to, opposing ends of lowering of the block HI may be controlledby a strong coil spring l8 which links the connectors together. Thisspring l8 and connectors l6, l1 may be specifically designed for eachsize and type of overhead crane.

The lower end of the lower connector i1 is formed into a fork l9 andbetween the arms of this fork there is a sheave 20, over which thehoisting cable is looped (as shown in Figure 4) and which sheave ismounted to rotate on a spindle 2| whose ends have hearings in the armsof the fork l9.

There is a bridle formed of the side links 22, 22. The rod l5 passesthrough the upper ends of these side links so that they are suspendedtherefrom and the lower ends of the side links have aligned verticalslots 23, 23 through which the ends of the spindle 2i extend. The links22, 22 are spaced from the upper connector by means of the spacers 24,24 which are located between said links and said connector and throughwhich the rod l5 extends and the lower ends of said links are spacedfrom the yoke l9 by the spacers 25, 25 which are located between saidlower connector and said yoke and through which the spindle 2| extends.The lower ends of the links 22 are maintained against spreading androtation by means of washers 26, 26 which are keyed on to theirrespective ends of the spindle 2i.

The bridle above described limits the range of downward movement of thelower'connector l1 relative to the upper connector It in the event ofany structural failure of the spring I8 or the connectors l6 and i1,thus preventing an accident as a result of such failure.

As illustrated in Figures 4 and 5 there is a series of contacts 21, 28,29, 30, 3i and 32, which are mounted on the supporting plate 33 fixed tov the upper connector i6 and there is a flexible contact arm 34 one endof which is fixed to a suitable anchor 35 carried by the supportingplate 36 which is mounted on the lower connector [1. The other end ofsaid arm 34 is adapted to successively form electrical connections withthe contacts 21 to 32, inclusive.

There is an indicator panel 31 in front 01 the operator stationed in theoperator's cab 38 and on this panel are the weight-indicating electricalsignal lights which indicate the load supported from the traveling blockI 0. As an illustration the light 21a may indicate a relatively lightload, the light 28a may indicate a heavier load and so on with thelights 29a, Ma, Ma and 32a all as predetermined for each application.These lights are connected with the respective contacts 21 to 32,inclusive, by the wiring 21b, 28b, 29b, 30b, Nb, and 32b, which, inturn, are also connected into the main electrical conductors 39 and 40,the later of which is electrically connected with the contact arm 34.

There is also a shut-down contact 4| with which the contact arm forms anelectrical connection when a predetermined load limit has been reachedand which is connected into the main circuit through the wiring 42. Arelay 43 is connected into the circuit 42 and is adapted to operate anaudible alarm, or a brake mechanism, or both, designated generally bythe numeral 44. The brake mechanism, if used, is provided to set thebrakes on the hoisting motorto prevent excessive overloading of thecrane and the audible alarm is arranged to operate immediately prior tothe setting of the brakes.

Wired into the main electrical circuit are also a series of troublelights 21c, 28c, 29c, 30c, 3lc and 320. These lights are arranged tocorrespond with the signal lights 21a to 32a, respectively. They areconstantly illuminated except when the circuit through the correspondingsignal light is out of order and are provided to indicate to theoperator whether or not the signal lights are in working order. They areof high resistance and therefore will be constantly illuminated, whenthe signal lights are in order.

There is a resistor 45 connected to the conductor 40 and which is inseries with the contact arm 34 so as to provide suiiicient voltageacross said resistor to illuminate the lights 21c to 32c, inelusive,while the contact arm 34 is in contact with any one of the contacts 21to 32, inclusive, and at which time signal light, corresponding to thecontact with which the contact arm 34 is in electrical connection, willbe illuminated.

The electrical conductors 39 and 40 lead to the panel 31 from the sourceof electrical energy. From the panel to the contacts electricalconductor 40 and electrical conductors 21b through 32b and alsoelectrical conductor 42 are enclosed within a suitable flexible cable,as 48, or they may be in the form of rigid conductors fastened directlyto the crane.

It is, of course, obvious that the lower connector I! may be supporteddirectly from the crane and the upper connector may be mountedyieldingly on the spring is and the sheave 20 suspended from said upperconnector. This would be merely a reversal of parts and the spring Itwould then be a compression spring. In this connection it is to be notedgenerally that the drawings and description disclose only what is nowconsidered to be a preferred form of the invention by way ofillustration, merely, while the broad principle of the invention will bedefined by the appended claims.

What I claim is:

1. In a, load indicator for overhead cranes, a e tension signalactuating unit comprising, an upper connector suspended from the cranetrolley, a lower connector, a coil spring into whose ends the adjacentends of the connectors are threaded, said spring linking the connectorstogether yieldingly, a series or electrical contacts stationary withrespect to one connector, a contact member fixed relative to the otherconnector, said contact member and contacts being arranged to formsuccessive electrical connections upon relative movement of saidconnectors.

2. In a load indicator for overhead cranes, a line tension signalactuating unit comprising, an upper connector suspended from the cranetrolley, .a lower connector, a coil spring into whose ends the adjacentends of the connectors are threaded, said spring linking the connectorstogether yieldingly, a series of electrical contacts stationary withrespect to one connector, 9. contact member fixed relative to the otherconnector, said contact member and contacts being arranged to formsuccessive electrical connections upon relative movement of saidconnectors, and a series of electrical signals electrically connectedwith the series of electrical contacts.

3. In a load indicator for overhead cranes, a line tension signalactuating unit comprising, an upper connector, a lower connector, one ofsaid connectors being attached to the crane, a helical spring directlylinking the connectors together, a load supporting sheave mounted on theother connector, a bridle including side links whose upper ends areattached to the crane and with which the sheave has a limited, slidable,connection, a series of electrical contacts stationary with respect toone connector, 8. contact member stationary with respect to the otherconnector, said contact member and contacts being arranged to formsuccessive electrical connections upon relative movement of said upperand lower connectors,

4. In a load indicator for overhead cranes, a line tension signalactuating unit comprising, an upper connector attached to the crane, alower connector, a tension spring linking the connectors together, aload supporting sheave mounted on the lower connector, a bridleincluding side links whose upper ends are attached to the crane and withwhose lower ends the sheave has a limited, slidable, connection, aseries of electrical contacts stationary with respect to one connector,a contact member stationary with respect to the other connector, saidcontact member and contacts being arranged to form successive electricalconnections upon relative movement of said upper and lower connectors,and a series of electrical signals which are electrically connected withthe respective electrical contacts.

5. In a load indicator for overhead cranes, a line tension signalactuatingunit comprising, an upper connector attached to the crane, alower connector, a tension spring linking the connectors together, abridle including side links whose upper ends are attached to the crane.and whose lower ends are formed with oblong, vertical bearings, a sheaveaxle on the lower connector whose ends are slidable in said bearings, aload supporting sheave mounted on said axle and electrical contactmembers on said connectors relatively movable with said connectors tocomplete an electrical circuit to a signal device.

6. In a. load indicator for overhead cranes, a line tension signalactuating unit comprising, an upper connector attached to the crane, alower connector, a tension spring linking the connectors together, abridle including side links whose upper ends are attached to the craneand whose lower ends are formed with oblong, vertical bearings, a sheaveaxle on the lower connector whose ends are slidable in said bearings, aload supporting sheave mounted on said axle, a series of electricalcontacts stationary with respect to one connector, a contact memberstationary with respect to the other connector, said contact member andcontacts being arranged to form successive electrical connections uponrelative movement of said connectors.

7. In a load indicator for overhead cranes, a line tension signalactuating unit comprising, an upper connector, 9. lower connector, oneof said connectors being attached to the crane, a helical springyieldingly supporting the other connector and linking the connectorstogether, means for attaching a load to the yiei'dingly mountedconnector, means for limiting the range or movement of one connectorrelative to the other connector, a series of electrical contactsstationary with respect to one connector, a contact member stationarywith respect to the other connector, said contact member and contactsbeing arranged to form successive electrical connections upon relativemoveme t of said connectors under the influence of said load and aseries of electrical signals electrically connected with the series ofelectrical contacts.

8. In a load indicator for overhead cranes, a line tension signalactuating unit comprising, an upper connector, a lower connector, one ofsaid connectors being attached to the crane, a helical spring connectedtosaid connectors linking n. s. ADAMS.

REFERENCES CITED The following references are of record in the file 'ofthis patent:

UNITED STATES PATENTS Number Number Name- Date Bull Jan. 22, 1895 LarsonDec. 16, 1913 Riley Aug. 28, 1917 Cardone Mar. 25, 1919 Butusov Apr. 20,1926 Hallenbeck Dec. 13, 1932 Hallenbeck Dec. 13, 1932 FOREIGN PATENTSCountry Date Great Britain Feb. 19, 1920 France Mar. 17, 1921

